LB7: Low Coolant?

[OnixMax]

Hi all,

I've got an 03 Silverado 2500HD LB7. Just rolled 200k on the odometer.
This morning, I got a low coolant light. I didn't see any leaks running, or not running.

Background on truck:
Bought at 185k.
All 8 injectors at 190k. Lifted 2 cups, and re-loctited and reset them.
Swap to Zerex G-05 coolant when injectors were done.
Don't smell any out the tailpipe.

Any ideas? Maybe a SMALL leak into the cylinders?

 

[bonomax]

possible headgasket leak. do you see any tiny bubbles coming up from the overflow coolant tank?

 

[Chevy1925]

how many miles on it since the injectors? did you not reseal ALL the injector cups when you pull the injectors?

 

[ThebigGids]

Have you noticed any extreme pressure in the cooling system?

I'd lean towards injector cups then HGs. Could also take a look at the wp to see if its been leaking

 

[OnixMax]

possible headgasket leak. do you see any tiny bubbles coming up from the overflow coolant tank?

Coolant overflow tank doesn't have any bubbles, no

how many miles on it since the injectors? did you not reseal ALL the injector cups when you pull the injectors?

About 9,500 miles. I only resealed the cups that came out with the injectors. That said, I did verify that they were all seated properly.

Have you noticed any extreme pressure in the cooling system?

I'd lean towards injector cups then HGs. Could also take a look at the wp to see if its been leaking

I can easily squeeze the upper radiator hose after the truck's been off.
I'm wondering if maybe there is a slow hg leak or a slow cup leak. Next oil change I'm gonna send a sample to Blackstone Labs and see what they say

 

[OnixMax]

I'm installing my S&B intake this weekend, so I'm gonna get underneath and see if I can see any leakage from the water pump, or otherwise.

I'm also gonna throw some more G05 in there and see what happens

 

[Chevy1925]

About 9,500 miles. I only resealed the cups that came out with the injectors. That said, I did verify that they were all seated properly.

you more than likely just found your issue . just because you didnt pull a cup out with the injector does NOT mean you did not break the seal. i just replaced 2 injectors in my truck and neither cup pulled out but i made damn sure to pull the cups anyhow and reseal them. its an extra 30 min to reseal all the cups on a days injectors job, i will never understand why people wont do it. you have no way of actually verifying the cup is good and still sealed in place. the only way to do it is to pull it, clean the area, and re seal.

sorry for the little rant but i know some people preach out there that if the cup doesnt come out, it is sealed up still and will be fine. its a crock of bs. the little movement the o-rings at the top of the cup as well as the movement the injector causes when removing it can break or crack the hard loctite and you will never know it.

 

[OnixMax]

you more than likely just found your issue . just because you didnt pull a cup out with the injector does NOT mean you did not break the seal. i just replaced 2 injectors in my truck and neither cup pulled out but i made damn sure to pull the cups anyhow and reseal them. its an extra 30 min to reseal all the cups on a days injectors job, i will never understand why people wont do it. you have no way of actually verifying the cup is good and still sealed in place. the only way to do it is to pull it, clean the area, and re seal.

sorry for the little rant but i know some people preach out there that if the cup doesnt come out, it is sealed up still and will be fine. its a crock of bs. the little movement the o-rings at the top of the cup as well as the movement the injector causes when removing it can break or crack the hard loctite and you will never know it.

Fair. That said, I filled the coolant to the 'Cold' line and it took almost 10k miles to get low. With that slow of a leak (assuming that it's a cup), is it worth tearing back into it?
Should also be noted that I get NO smoke of any kind when at idle, or normal driving.

 

[Chevy1925]

when i had a HG go, all it would do is sip coolant. ive seen cups do the same thing. fill her up and see if it happens again. if it does, id be tearing it down and resealing all the cups.

you might be able to pressurize the system, leave the glow plugs out, and let it sit pressized over night. then have someone watching both sides of the truck as you crank it over in the moring to see where coolant comes out (if it even leaked any) to hopefully pin point a cyl.

 

[OnixMax]

when i had a HG go, all it would do is sip coolant. ive seen cups do the same thing. fill her up and see if it happens again. if it does, id be tearing it down and resealing all the cups.

you might be able to pressurize the system, leave the glow plugs out, and let it sit pressized over night. then have someone watching both sides of the truck as you crank it over in the moring to see where coolant comes out (if it even leaked any) to hopefully pin point a cyl.

I'll fill her up and keep a close eye. Worst comes to worst, take the damn thing apart again lol.


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